Vulnerability in Microsoft Windows 10
CVE-2021-26887
<p>An elevation of privilege vulnerability exists in Microsoft Windows when Folder redirection has been enabled via Group Policy. When folder redirection file server is co-located with Terminal server, an attacker who successfully exploited the vulnerability would be able to begin redirecting another user's personal data to a created folder.</p> <p>To exploit the vulnerability, an attacker can create a new folder under the Folder Redirection root path and create a junction on a newly created User folder. When the new user logs in, Folder Redirection would start redirecting to the folder and copying personal data.</p> <p>This elevation of privilege vulnerability can only be addressed by reconfiguring Folder Redirection with Offline files and restricting permissions, and NOT via a security update for affected Windows Servers. See the <strong>FAQ</strong> section of this CVE for configuration guidance.</p>
EPSS: 0.009 (56.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Microsoft Windows_10 — versions 20h2, 1607, 1803
- Microsoft Windows 10 Version 1507 — versions N/A
- Microsoft Windows 10 Version 1607 — versions N/A
- Microsoft Windows 10 Version 1803 — versions N/A
- Microsoft Windows 10 Version 1809 — versions N/A
- Microsoft Windows 10 Version 1909 — versions N/A
- Microsoft Windows 10 Version 2004 — versions N/A
- Microsoft Windows 10 Version 20h2 — versions N/A
- Microsoft Windows 7 — versions N/A
- Microsoft Windows_7
Weakness classification (CWE)
Public proof-of-concept exploits
References
- secure@microsoft.com (Patch, x_refsource_MISC, Vendor Advisory)
Frequently asked questions
- What is CVE-2021-26887?
- CVE-2021-26887 is a high-severity vulnerability in Microsoft Windows 10, classified under Improper Link Resolution Before File Access. CVSS score: 7.8/10. Published 2021-03-11.
- How severe is CVE-2021-26887?
- High severity. CVSS v3 base score is 7.8 out of 10.
- Is CVE-2021-26887 known to be exploited?
- 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.